Compartmental study of T 1 and T 2 in rat brain and trigeminal nerve in vivo

The integrated T 1 – T 2 characteristics of rat brain and trigeminal nerve water were studied in vivo using a rapid method for acquiring a series of images that depend on T 1 and T 2 relaxation times. Gray matter regions showed only one signal component in both the T 1 and T 2 domains. Trigeminal nerve, however, which has been shown previously to exhibit three T 2 components, was found to also exhibit three T 1 components. The correlations between these T 1 and T 2 components were demonstrated by uniquely filtering out each of the three T 2 components using an inversion‐recovery preparation, as determined by the component T 1 values. Based on previous works, it is postulated that each of these three signal components is derived from a unique microanatomical region of the nerve. Knowledge of these T 1 components may thus prove valuable in devising novel methods of identifying the presence and quantifying the volume of tissue subtypes such as myelin. Magn Reson Med 47:274–283, 2002. © 2002 Wiley‐Liss, Inc.